1. Technical Field
The present invention relates to a projector, a projection system, and a method for generating pixel values in a projector.
2. Related Art
There has been known a method for using two projectors to project and overlay the same image on one screen (projection surface) (see JP-A-5-107639, for example). According to such a method, the brightness of the projected, overlaid image light is nearly doubled, and hence a high-brightness projected image can be achieved. Further, by projecting image light from two projectors in such a way that one of the images is displaced from the other by a half pixel, a high-definition projected image can be achieved.
In such overlay projection, however, it is not easy to accurately superimpose the image light from the two projectors on the screen. Inaccurate superimposition of the image light from the two projectors degrades the image quality of the projected image.
As a projector of related art capable of solving such a problem, there has been proposed a projector including a polarization separation system that separates the light from an illuminator into a light beam having a first polarization component and a light beam having a second polarization component and directs the resultant light beams toward two image formation units, and a polarization combining system that combines the image light beams from the two image formation units (see JP-A-1-126678, for example).
According to the projector of related art, the light from the illuminator is separated into the light beam having the first polarization component and the light beam having the second polarization component, and the image formation units form the image light beams. Then, the polarization combining system combines the two image light beams, and one projection system projects the combined light beam onto the screen. Therefore, provided that the two image formation units have been accurately positioned prior to shipping, the image light beams from the two image formation units can be accurately superimposed on the screen. As a result, it is possible to prevent reduction in image quality of the projected image.
In recent years, however, there is a need for a super high-definition, super-megapixel projector (such as a super-megapixel projector having 2K by 4K (2000 by 4000) pixels or 4K by 8K (4000 by 8000) pixels). In achieving such a super-megapixel projector, it has been found that there may be a problem of inaccurate projection of the light outputted from the image formation units on the projection surface (for example, when any possible positional alignment does not allow complete superimposition of the image light beams from the two image formation units on the projection surface, the pixels only in a specific area are not aligned on the projection surface) due to slightly insufficient accuracy in various optical elements (slight in-plane non-uniformity in a light modulation element (such as a liquid crystal panel) and accompanying optical elements (such as a polarizer and a viewing angle compensator), slight optical distortion and color aberration in the projection system, slightly insufficient accuracy in position and attitude of the light modulation element with respect to the projection system, and the like). Such a problem degrades the image quality of the projector. Such a problem can occur not only in a super-megapixel projector but also in an ordinary megapixel projector (a projector having 1080 by 1920 pixels and a projector having 720 pixel by 1280 pixels, for example).